Canister

摘要

In order to provide a filter structure for a canister in which dust or the like in air is prevented from sticking to the filter and being distributed over the entire surface thereof, and accordingly, the filter can hardly clogging so as to prevent lowering of the purge volume of a canister due to an increase in ventilation resistance, the dust filter 8 is formed in a crescent-like shape, having, at a substantially center thereof, a pipe hole 8a fitted on a pipe extended to a filter chamber le, the filter chamber le accommodating the dust filter 8 is formed in a crescent-like shape substantially identical with that of the dust filter 8 and the atmospheric port 1f is communicated with the bottom side of the dust filter 8, and accordingly, the atmospheric air flows by a large volume around the pipe 7a so that the dust or the like is likely to be accumulated around the pipe 7a, but the opposite ends becoming narrow outward so that the flow rate of the atmospheric air is become less. As a result, the dust or the like can hardly be accumulated so as to prevent the ventilation resistance of the dust filter 8 from increasing, thereby preventing leakage of evaporation fuel into the atmosphere. Further, in a canister, in order to aim at restraining the ventilation resistance of the filter from being increased by dust sucked with air through the atmospheric port, and at enhancing the mounting ability of the filter for restraining suction of the dust, the atmospheric port 33 is formed in the upper portion of a canister casing 31, dust sucked through the atmospheric port 33 being caused to stick to the lower surface of a dust preventing filter 34 while the sticking dust is allowed to be dropped by vibration. Further, the dust preventing filter 34 is held by a filter holding member 35, and is then fitted in a filter mounting chamber 39 defined in the canister casing 31. Thereafter, an adsorbent side filter 36 is secured. A temporary holding device A for temporarily holding the filter holding member is provided in the filter holding member 35 and the filter mounting chamber 39.